期刊文献+
共找到3,084篇文章
< 1 2 155 >
每页显示 20 50 100
The forecasting efficiency under different selected regions by Pattern Informatics Method and seismic potential estimation in the North-South Seismic Zone
1
作者 Weixi Tian Yongxian Zhang 《Earthquake Science》 2024年第4期368-382,共15页
In 2022,four earthquakes with M_(S)≥6.0 including the Menyuan M_(S)6.9 and Luding M_(S)6.8 earthquakes occurred in the North-South Seismic Zone(NSSZ),which demonstrated high and strong seismicity.Pattern Informatics(... In 2022,four earthquakes with M_(S)≥6.0 including the Menyuan M_(S)6.9 and Luding M_(S)6.8 earthquakes occurred in the North-South Seismic Zone(NSSZ),which demonstrated high and strong seismicity.Pattern Informatics(PI)method,as an effective long and medium term earthquake forecasting method,has been applied to the strong earthquake forecasting in Chinese mainland and results have shown the positive performance.The earthquake catalog with magnitude above M_(S)3.0 since 1970 provided by China Earthquake Networks Center was employed in this study and the Receiver Operating Characteristic(ROC)method was applied to test the forecasting efficiency of the PI method in each selected region related to the North-South Seismic Zone systematically.Based on this,we selected the area with the best ROC testing result and analyzed the evolution process of the PI hotspot map reflecting the small seismic activity pattern prior to the Menyuan M_(S)6.9 and Luding M_(S)6.8 earthquakes.A“forward”forecast for the area was carried out to assess seismic risk.The study shows the following.1)PI forecasting has higher forecasting efficiency in the selected study region where the difference of seismicity in any place of the region is smaller.2)In areas with smaller differences of seismicity,the activity pattern of small earthquakes prior to the Menyuan M_(S)6.9 and Luding M_(S)6.8 earthquakes can be obtained by analyzing the spatio-temporal evolution process of the PI hotspot map.3)The hotspot evolution in and around the southern Tazang fault in the study area is similar to that prior to the strong earthquakes,which suggests the possible seismic hazard in the future.This study could provide some ideas to the seismic hazard assessment in other regions with high seismicity,such as Japan,Californi,Turkey,and Indonesia. 展开更多
关键词 Luding M_(S)6.8 and Menyuan M_(S)6.9 earthquake pattern Informatics method North-South Seismic Zone earthquake forecasting seismic activity pattern.
下载PDF
An Efficient Pattern Search Method 被引量:1
2
作者 Xiaoli Zhang Qinghua Zhou Yue Wang 《Journal of Applied Mathematics and Physics》 2013年第4期68-72,共5页
Pattern search algorithms is one of most frequently used methods which were designed to solve the derivative-free optimization problems. Such methods get growing need with the development of science, engineering, econ... Pattern search algorithms is one of most frequently used methods which were designed to solve the derivative-free optimization problems. Such methods get growing need with the development of science, engineering, economy and so on. Inspired by the idea of Hooke and Jeeves, we introduced an integer m in the algorithm which controls the number of steps of iteration update. We mean along the descent direction to allow the algorithm to?go ahead m steps at most to explore whether we can get better solution further. The experiment proved the strategy’s efficiency. 展开更多
关键词 UNCONSTRAINED OPTIMIZATION DERIVATIVE-FREE OPTIMIZATION pattern SEARCH methods POSITIVE BASES
下载PDF
G-G PATTERNING METHOD OF SILK WEAVING IN EARLIER CHINA
3
作者 赵丰 《Journal of China Textile University(English Edition)》 EI CAS 1994年第2期1-10,共10页
There are some unique techniques in the Chinese traditional silk production. 2-2 patterning method is such one suggested by foreign scholars. But this paper gives a more extensive concept, G-G method, which includes t... There are some unique techniques in the Chinese traditional silk production. 2-2 patterning method is such one suggested by foreign scholars. But this paper gives a more extensive concept, G-G method, which includes the 2-2 method after studying more fabrics from the Shang. to the Five Dynasties. Finally, the paper discusses the truth of G-G method the (?) applied in, and some characteristics of G-G method. 展开更多
关键词 SILK HISTORY of technique. weave constructure patternING method
下载PDF
Low side lobe pattern synthesis using projection method with genetic algorithm for truncated cone conformal phased arrays 被引量:7
4
作者 Guoqi Zeng Siyin Li +1 位作者 Yan Zhang Shanwei L 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2014年第4期554-559,共6页
A hybrid method for synthesizing antenna's three dimensional (3D) pattern is proposed to obtain the low sidelobe feature of truncated cone conformal phased arrays. In this method, the elements of truncated cone con... A hybrid method for synthesizing antenna's three dimensional (3D) pattern is proposed to obtain the low sidelobe feature of truncated cone conformal phased arrays. In this method, the elements of truncated cone conformal phased arrays are projected to the tangent plane in one generatrix of the truncated cone. Then two dimensional (2D) Chebyshev amplitude distribution optimization is respectively used in two mutual vertical directions of the tangent plane. According to the location of the elements, the excitation current amplitude distribution of each element on the conformal structure is derived reversely, then the excitation current amplitude is further optimized by using the genetic algorithm (GA). A truncated cone problem with 8x8 elements on it, and a 3D pattern desired side lobe level (SLL) up to 35 dB, is studied. By using the hybrid method, the optimal goal is accomplished with acceptable CPU time, which indicates that this hybrid method for the low sidelobe synthesis is feasible. 展开更多
关键词 conformal phased array low side lobe pattern synthe-sis projection method genetic algorithm optimization.
下载PDF
A NEW METHOD FOR CONSTRUCTING DIGITAL-STRAIN-FIELD-IMAGES FROM MOIRE PATTERNS
5
作者 Yu Qifeng and Long DiboNational University of Defence Technology 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 1990年第1期16-22,共7页
A new method for constructing digital-strain-field-image from a moire pattern with the help of digital image processing technique is proposed in this paper. The digital-strain-field-image expresses the strain values d... A new method for constructing digital-strain-field-image from a moire pattern with the help of digital image processing technique is proposed in this paper. The digital-strain-field-image expresses the strain values directly by its grey levels. The digital-strain-field-image can be obtained by making a differentiation for the digital moire pattern and doing a simple division operation. This image not only gives the visual strain field distribution, but also gives the strain values of every point. This method is simple and applicable and has satisfactory accuracy. 展开更多
关键词 In A NEW method FOR CONSTRUCTING DIGITAL-STRAIN-FIELD-IMAGES FROM MOIRE patternS than
下载PDF
DETERMINATION OF THE FAVORED PATTERN IN NEURAL SPIKE TRAIN WITH MONTE CARLO METHOD AND TEMPLATE METHOD
6
作者 陈筱英 柴振明 《Journal of Electronics(China)》 1991年第4期378-382,共5页
The modern neuroelectrical physiology indicates that there are certain patterns inneural spike train which appear more frequently than others.These favored patterns(FP)maybe related to the mechanism of neural informat... The modern neuroelectrical physiology indicates that there are certain patterns inneural spike train which appear more frequently than others.These favored patterns(FP)maybe related to the mechanism of neural information processing in central nervous system.Inthis paper,the quantized Monte Carlo method and template method used in favored patternrecognition are described.The Monte Carlo method determines favored patterns or the possiblefavored patterns,while the template method is used for choosing the FP from the candidates andcounting the number of the FP in the spike train.This work will be pursued for extracting theFP in some complicated spike train. 展开更多
关键词 NEURAL SPIKE TRAIN FAVORED pattern MONTE Carlo method
下载PDF
Comparing Eight Computing Algorithms and Four Consensus Methods to Analyze Relationship between Land Use Pattern and Driving Forces
7
作者 Xinliang Liu Yi Wang +6 位作者 Yong Li Feng Liu Jianlin Shen Liang Ou Juan Wang Runlin Xiao Jinshui Wu 《International Journal of Geosciences》 2019年第1期12-28,共17页
Although many computing algorithms have been developed to analyze the relationship between land use pattern and driving forces (RLPDF), little has been done to assess and reduce the uncertainty of predictions. In this... Although many computing algorithms have been developed to analyze the relationship between land use pattern and driving forces (RLPDF), little has been done to assess and reduce the uncertainty of predictions. In this study, we investigated RLPDF based on 1990, 2005 and 2012 datasets at two spatial scales using eight state-of-the-art single computing algorithms and four consensus methods in Jinjing rive catchment in Hunan Province, China. At the entire catchment scale, the mean AUC values were between 0.715 (ANN) and 0.948 (RF) for the single-algorithms, and from 0.764 to 0.962 for the consensus methods. At the subcatchment scale, the mean AUC values between 0.624 (CTA) and 0.972 (RF) for the single-algorithms, and from 0.758 to 0.979 for the consensus methods. At the subcatchment scale, the mean AUC values were between 0.624 (CTA) and 0.972 (RF) for the single-algorithms, and from 0.758 to 0.979 for the consensus methods. The result suggested that among the eight single computing algorithms, RF performed the best overall for woodland and paddy field;consensus method showed higher predictive performance for woodland and paddy field models than the single computing algorithms. We compared the simulation results of the best - and worst-performing algorithms for the entire catchment in 2012, and found that approximately 72.5% of woodland and 72.4% of paddy field had probabilities of occurrence of less than 0.1, and 3.6% of woodland and 14.5% of paddy field had probabilities of occurrence of more than 0.5. In other words, the simulation errors associated with using different computing algorithms can be up to 14.5% if a probability level of 0.5 is set as the threshold. The results of this study showed that the choice of modeling approaches can greatly affect the accuracy of RLPDF prediction. The computing algorithms for specific RLPDF tasks in specific regions have to be localized and optimized. 展开更多
关键词 LAND Use pattern Spatial Scales CONSENSUS methods COMPUTING ALGORITHMS
下载PDF
Antenna Array Pattern Synthesis via Coordinate Descent Method
8
作者 Yuanhao Wang Xiaoxi He +2 位作者 Jiangning Wang Sergey Berezin Wolfgang Mathis 《Journal of Electromagnetic Analysis and Applications》 2015年第5期168-177,共10页
This paper presents an array pattern synthesis algorithm for arbitrary arrays based on coordinate descent method (CDM). With this algorithm, the complex element weights are found to minimize a weighted L2 norm of the ... This paper presents an array pattern synthesis algorithm for arbitrary arrays based on coordinate descent method (CDM). With this algorithm, the complex element weights are found to minimize a weighted L2 norm of the difference between desired and achieved pattern. Compared with traditional optimization techniques, CDM is easy to implement and efficient to reach the optimum solutions. Main advantage is the flexibility. CDM is suitable for linear and planar array with arbitrary array elements on arbitrary positions. With this method, we can configure arbitrary beam pattern, which gives it the ability to solve variety of beam forming problem, e.g. focused beam, shaped beam, nulls at arbitrary direction and with arbitrary beam width. CDM is applicable for phase-only and amplitude-only arrays as well, and furthermore, it is a suitable method to treat the problem of array with element failures. 展开更多
关键词 ANTENNA Phased ARRAY Optimization pattern Synthesis COORDINATE DESCENT method
下载PDF
Experimental Research on the Erosion Pattern and Protection Using the Extended Modelling Method
9
作者 Liu Shunkuan Senior Engineer, Tianjin Port Engineering Institute, Tianjin 300222 《China Ocean Engineering》 SCIE EI 1997年第4期441-448,共8页
In the paper the extended modelling method with serial sands is used in an experimental research on the erosion patterns at the discharge outlet of a beach Hua-Neng power plant. The theoretical basis for the extended ... In the paper the extended modelling method with serial sands is used in an experimental research on the erosion patterns at the discharge outlet of a beach Hua-Neng power plant. The theoretical basis for the extended modelling method with serial sands is systematically presented in the paper and the method has been successfully employed in the sediment experiment of coastal works. According to the Froude Law, the model is designed to be a normal one with movable bed, the geometric scale lambda(L) = lambda(H) = 15, and three scales of sediment grain size are chosen, i.e., lambda(d1) = 0.207; lambda(d2) = 0.393; and lambda(d3) = 0.656. The median particle diameter of sea beach prototype sand d(50p) = 0.059 mm and the dis-changed water flow of the power plant is 21.7 m(3) / s. Three types of natural sea sands have been chosen as the serial modelling sands to extend the simulation of the prototype, thus replacing the conventional test in which artificial lightweight sands are used. As a result, this method can not only reduce the cost significantly, but also it is an advanced technique easy to use. Upon a series of tests, satisfactory results have been obtained. 展开更多
关键词 extended modelling method discharge outlet erosion pattern beach protection
下载PDF
伊犁河三角洲水资源条件变化对景观格局演变的影响 被引量:1
10
作者 陈启慧 纪璐 +6 位作者 李琼芳 白浩男 韩幸烨 姚佳 崔罡 周正模 杨坤凡 《水资源保护》 EI CAS CSCD 北大核心 2024年第2期90-99,共10页
在分析1992—2020年伊犁河三角洲水资源条件和定量评估研究期内土地利用变化的基础上,选取景观类型水平和景观水平指数解析景观格局变化特征,采用皮尔逊相关系数分析了水资源条件变化对景观格局指数的影响。结果表明:乌斯热尔玛水文站... 在分析1992—2020年伊犁河三角洲水资源条件和定量评估研究期内土地利用变化的基础上,选取景观类型水平和景观水平指数解析景观格局变化特征,采用皮尔逊相关系数分析了水资源条件变化对景观格局指数的影响。结果表明:乌斯热尔玛水文站年径流总体偏大,巴尔喀什湖年平均水位在2002年发生突变,三角洲水资源补给总体处于增加状态;湿地和稀疏植被面积增大且聚集性增强,裸地向稀疏植被转化且优势度不断下降,林地破碎程度剧烈;景观水平指数在时程上呈阶段性变化,2016年伊犁河三角洲破碎化程度最低,在空间上伊犁河沿岸连通性增强,巴尔喀什湖沿岸景观多样性增加;景观水平指数与巴尔喀什湖年平均水位相关性最高,与乌斯热尔玛水文站年径流量的相关性次之,与伊犁河三角洲年降水量的相关性最低,且景观水平指数对三角洲水资源条件变化存在迟滞响应。 展开更多
关键词 景观格局 水资源 移动窗口法 土地利用 伊犁河三角洲
下载PDF
深部破碎软岩巷道超前控顶加固及控制爆破技术
11
作者 汪禹 张西良 +4 位作者 李龙福 殷登才 崔正荣 王小兵 金科 《爆破》 CSCD 北大核心 2024年第3期75-84,共10页
随着矿山开采深度逐渐增加,深部破碎围岩工程地质条件转为复杂多变,极大程度上影响巷道等工程施工过程及后续使用安全;为确保深部破碎软岩巷道施工过程中安全及质量,提出了软岩巷道超前控顶加固及控制爆破技术。针对钟九铁矿-550 m水平... 随着矿山开采深度逐渐增加,深部破碎围岩工程地质条件转为复杂多变,极大程度上影响巷道等工程施工过程及后续使用安全;为确保深部破碎软岩巷道施工过程中安全及质量,提出了软岩巷道超前控顶加固及控制爆破技术。针对钟九铁矿-550 m水平6号交岔点岩体裂隙极为发育、稳定性差等特点,拟采用超前控顶措施加固顶板围岩,提高深部破碎软岩巷道的承载力。为便于6号交岔点掘进施工,沿6号交岔点东北侧方向划分17个掘进区,并采用“四步”台阶法分段施工。针对同段起爆数码电子雷管,起爆器系统可随机设置单发雷管起爆间隔时间为3~5 ms,实现同段炮孔单孔单响,降低爆破振动对6号交岔点影响。根据不同掘进区总体岩性情况,优化支护方式(管棚支护、W型钢带及锚索支护等联合支护方式等),确保6号交岔点后续使用期安全。试验结果表明:采用超前控顶加固、控制分区爆破技术,降低破碎软岩巷道顶板偏帮、下沉,保证6号交岔点断面成型效果,削减其支护、后期维护等综合成本达8.7%,该技术可为类似巷道施工提供一定指导建议。 展开更多
关键词 破碎软岩 台阶法施工 支护方式 数码电子雷管
下载PDF
Fault Pattern Recognition based on Kernel Method and Fuzzy C-means
12
作者 SUN Yebei ZHAO Rongzhen TANG Xiaobin 《International Journal of Plant Engineering and Management》 2016年第4期231-240,共10页
A method about fault identification is proposed to solve the relationship among fault features of large rotating machinery, which is extremely complicated and nonlinear. This paper studies the rotor test-rig and the c... A method about fault identification is proposed to solve the relationship among fault features of large rotating machinery, which is extremely complicated and nonlinear. This paper studies the rotor test-rig and the clustering of data sets and fault pattern recognitions. The present method firstly maps the data from their original space to a high dimensional Kernel space which makes the highly nonlinear data in low-dimensional space become linearly separable in Kernel space. It highlights the differences among the features of the data set. Then fuzzy C-means (FCM) is conducted in the Kernel space. Each data is assigned to the nearest class by computing the distance to the clustering center. Finally, test set is used to judge the results. The convergence rate and clustering accuracy are better than traditional FCM. The study shows that the method is effective for the accuracy of pattern recognition on rotating machinery. 展开更多
关键词 Kernel method fuzzy C-means FCM pattern recognition CLUSTERING
下载PDF
我国旅游消费现代化时空特征及影响因素分析
13
作者 刘聪 马丽君 李雯静 《昆明学院学报》 2024年第4期91-104,共14页
文章界定了旅游消费现代化的概念并构建其评价指标体系。利用CRITIC法计算了2011~2019年31个省市区旅游消费现代化指数,分析其时空分布格局及其影响因素。结果表明:(1)大部分省市区旅游消费现代化指数呈逐年上升的时间趋势,发展不平衡... 文章界定了旅游消费现代化的概念并构建其评价指标体系。利用CRITIC法计算了2011~2019年31个省市区旅游消费现代化指数,分析其时空分布格局及其影响因素。结果表明:(1)大部分省市区旅游消费现代化指数呈逐年上升的时间趋势,发展不平衡程度存在微弱的上升趋势;(2)旅游消费现代化存在区域异质,东部发展较好,中部和东北呈波动上升趋势,西部呈波动变化趋势;(3)旅游消费现代化水平存在空间正自相关,且程度呈增强的态势,集聚效果愈发显著。多数省市区旅游消费现代化属于低-低正自相关的集聚类型,且此类型的省市区逐年增加。(4)经济发展水平、人口、数字化、科技创新、政府干预均对旅游消费现代化有显著的正向影响。 展开更多
关键词 中国式现代化 旅游消费 时空特征 CRITIC赋值法 莫兰指数
下载PDF
天山北坡经济带城乡聚落格局变化与影响因素分析
14
作者 郑旭东 王宏卫 +2 位作者 罗魁 吴常蕊 闫晓梅 《华侨大学学报(自然科学版)》 CAS 2024年第3期383-393,共11页
以天山北坡经济带城乡聚落为研究对象,采用景观格局指数、地理信息系统(GIS)空间分析、位序-规模法等分析1980-2020年间城乡聚落格局的变化,结合地理探测器从自然、区位及社会经济因素探究城乡聚落格局的影响因素。结果表明:1980-2020年... 以天山北坡经济带城乡聚落为研究对象,采用景观格局指数、地理信息系统(GIS)空间分析、位序-规模法等分析1980-2020年间城乡聚落格局的变化,结合地理探测器从自然、区位及社会经济因素探究城乡聚落格局的影响因素。结果表明:1980-2020年间,城乡聚落数量、规模持续扩张且趋于集聚,前20 a扩张以耕地、草地为主,后20 a以未利用地为主;城乡聚落密度变化显著,高密度区主要集中在各绿洲呈现“多核集中分布”特征,中密度区沿高密度区周围扩张,低密度区沿绿洲边缘分布并在非绿洲区有扩张;首位聚落规模发展较好,趋于位序-规模曲线,中型聚落略微发育,小型聚落数量持续减少;交通等区位因素是天山北坡城乡聚落格局的首位影响因素,社会经济因素次之,自然地理因素影响较小,各影响因素差异显著。 展开更多
关键词 城乡聚落 景观格局 位序-规模法 地理探测器 天山北坡经济带
下载PDF
新疆烤羊肉串中杂环胺的生成规律研究进展 被引量:1
15
作者 李惠霖 龚誉 +5 位作者 赵新豪 黄万挺 邱苑振 沈幸 柴仲平 曾茂茂 《食品安全质量检测学报》 CAS 2024年第7期45-53,共9页
烤羊肉串,作为新疆特色美食,以其引人入胜的外观和独特的风味深受广大消费者追捧。然而,这类经过高温加工的食品容易产生多种致癌物质,其中之一就是杂环胺。杂环胺主要源自富含蛋白质的动物性食品,具有强烈的致癌和致突变特性。过量摄... 烤羊肉串,作为新疆特色美食,以其引人入胜的外观和独特的风味深受广大消费者追捧。然而,这类经过高温加工的食品容易产生多种致癌物质,其中之一就是杂环胺。杂环胺主要源自富含蛋白质的动物性食品,具有强烈的致癌和致突变特性。过量摄入将会提高人体患癌风险,对人体健康构成严重威胁。杂环胺的生成与反应底物、加工方式以及加工条件等密切相关。本文总结了杂环胺在热加工肉类中的分布状况及其生成的主要因素,重点综述了新疆特色美食烤羊肉串中杂环胺的生成规律以及抑制策略,旨在为今后新疆烤羊肉串的绿色加工以及杂环胺的减控方法提供科学理论依据,对消费者的健康饮食具有重要的指导意义。 展开更多
关键词 新疆 烤羊肉串 杂环胺 生成规律 抑制方法
下载PDF
蒙古族团花纹数字化创新设计研究 被引量:2
16
作者 杨冰云 闫丽霞 +1 位作者 张甜 孙卓薇 《包装工程》 CAS 北大核心 2024年第4期235-243,共9页
目的解决蒙古族团花纹应用时,因卷曲纹样基元形态提取不规范而导致的应用效果不佳问题,为蒙古族传统纹样的创新设计提供新的思路。方法本文以蒙古族团花纹为例,提出了一种数字化创新设计方法并加以实践。首先,从纹样的基元、结构、色彩... 目的解决蒙古族团花纹应用时,因卷曲纹样基元形态提取不规范而导致的应用效果不佳问题,为蒙古族传统纹样的创新设计提供新的思路。方法本文以蒙古族团花纹为例,提出了一种数字化创新设计方法并加以实践。首先,从纹样的基元、结构、色彩三方面对蒙古族传统纹样进行艺术特征分析,解读不同纹样的文化内涵并归纳造型特征。随后,通过数字化手段提取纹样基元,利用函数曲线替换其比例失衡的线条,进而规范纹样基元,提升纹样美观度。结果规范后的纹样基元运用形状文法进行创新设计,使纹样得到创新的同时在视觉形象上也有所提升。结论该方法既保留了蒙古族传统纹样的风格特征,又符合现代设计的审美需求,丰富了蒙古族传统纹样在进行当代产品应用时的设计方法。 展开更多
关键词 蒙古族团花纹 数学方法 数字化设计 形状文法
下载PDF
猪流行性腹泻病毒变异毒株一步法RT-PCR鉴别检测方法的建立及临床应用
17
作者 龚婷 马辉 +1 位作者 郭宏伟 郑鸣 《黑龙江畜牧兽医》 CAS 北大核心 2024年第7期18-22,29,共6页
为了建立一种快速鉴别检测猪流行性腹泻病毒(PEDV)变异毒株的病原学方法和掌握洛阳市PEDV变异毒株的流行规律,试验根据GenBank中PEDV变异毒株的特异性序列设计引物,通过优化退火温度、模板添加量、引物添加量建立PEDV变异毒株一步法RT-... 为了建立一种快速鉴别检测猪流行性腹泻病毒(PEDV)变异毒株的病原学方法和掌握洛阳市PEDV变异毒株的流行规律,试验根据GenBank中PEDV变异毒株的特异性序列设计引物,通过优化退火温度、模板添加量、引物添加量建立PEDV变异毒株一步法RT-PCR鉴别检测方法,并分析了该方法的特异性、敏感性和重复性;同时应用该方法检测采集自洛阳市的251份临床样品,并对不同地区、不同年份、不同养殖模式的检测结果进行比较分析。结果表明:优化后的退火温度为51℃,模板添加量为5μL,引物添加量为0.5μL;该方法对PEDV变异毒株能够扩增出550 bp特异性条带,而检测的PEDV经典毒株、猪传染性胃肠炎病毒(TGEV)、猪轮状病毒(RV)、猪繁殖与呼吸综合征病毒(PRRSV)、猪瘟病毒(CSFV)、猪细小病毒(PPV)、猪伪狂犬病病毒(PRV)、猪圆环病毒2型(PCV-2)均为阴性;对PEDV变异毒株RNA的最低检测限达到0.74 ng,对3份PEDV变异毒株阳性病料和3份PEDV变异毒株阴性病料重复检测3次的结果完全一致;检测采集于洛阳市251份临床样品的平均阳性率为29.48%,其中不同地区阳性率介于13.33%~44.44%之间,2018—2022年阳性率介于28.30%~31.58%之间,散养户和规模化猪场的阳性率分别为38.24%和19.13%。说明试验建立的PEDV变异毒株一步法RT-PCR鉴别检测方法特异、敏感、稳定、准确,洛阳市PEDV变异毒株的流行特点为个别地区较严重的情况、近几年流行率基本持平、散养户流行情况较规模化猪场严重。 展开更多
关键词 猪流行性腹泻病毒 变异毒株 一步法RT-PCR鉴别检测方法 临床应用 流行规律
下载PDF
基于点模式匹配的直流输电VBE设备电路板缺陷检测方法 被引量:1
18
作者 刘隆晨 杨玥坪 +3 位作者 陈少卿 张鹏 曹运龙 余人 《电源学报》 CSCD 北大核心 2024年第3期272-280,共9页
随着特高压直流输电技术飞速发展,换流阀阀基电子VBE(valve base electronics)设备的稳定性对于保障直流输电的可靠性和效率至关重要。VBE设备电路板缺陷,如短路和失效元件,直接影响直流系统稳定性,而现有的检测方法,包括人工显微镜检... 随着特高压直流输电技术飞速发展,换流阀阀基电子VBE(valve base electronics)设备的稳定性对于保障直流输电的可靠性和效率至关重要。VBE设备电路板缺陷,如短路和失效元件,直接影响直流系统稳定性,而现有的检测方法,包括人工显微镜检查和自动检测算法,常受限于效率低和准确性不足。针对该问题,提出一种基于点模式匹配的自动视觉检测方法,通过生成代表关键区域的点模式并进行匹配来提高检测的效率和准确率。通过实验验证,所提方法在检测速度和准确性方面相较于传统方法有显著提升,适合于生产线上的快速质量控制,为提高直流输电设备的质量提供了有效的技术方案。 展开更多
关键词 阀基电子设备 缺陷检测 点模式匹配方法 图像数据分析
下载PDF
基于离散元的采空诱发山体滑塌失稳模式研究 被引量:1
19
作者 马杰 何开明 +1 位作者 常文斌 邢爱国 《水文地质工程地质》 CAS CSCD 北大核心 2024年第3期171-179,共9页
采空诱发的山体崩滑是煤矿山区常见的一类灾害形式,为明确采动作用下采空山体的变形失稳模式,对典型采空控制型滑坡进行现场调查,采用颗粒离散元方法模拟单层采空与三层采空两种工况下反倾煤层斜坡的失稳破坏过程,并对斜坡变形过程中裂... 采空诱发的山体崩滑是煤矿山区常见的一类灾害形式,为明确采动作用下采空山体的变形失稳模式,对典型采空控制型滑坡进行现场调查,采用颗粒离散元方法模拟单层采空与三层采空两种工况下反倾煤层斜坡的失稳破坏过程,并对斜坡变形过程中裂纹扩展及岩体破碎特征进行分析。结果表明:(1)单层开挖工况中,煤层开挖后顶板区域会产生拱圈型的变形带并随之演化为冒落岩体,多层开挖的采空区间隔岩体则会发生弯曲状沉陷垮落,形成大面积的岩体破碎;(2)不同开挖工况下,冒落带形成及应力重分布初期,斜坡内部裂纹演化及岩体破碎皆较为缓慢,顶板冒落及岩层弯曲断裂阶段为岩体断裂破碎的关键阶段;(3)反倾煤层采空控制型山体失稳模式主要为煤层采空-顶板拱圈状冒落-内部岩层弯曲沉陷-后缘拉裂破碎-坡脚锁固区失效-破碎岩体浅层滑动。研究结果为采空控制型斜坡失稳机理分析提供了新的方向,为矿区滑坡灾害的防治提供了科学依据。 展开更多
关键词 采矿诱发 山体崩滑 岩体破碎 失稳模式 离散元
下载PDF
京津冀地区高质量发展水平综合评价与预警
20
作者 金剑 宋美辰 范小宁 《中国商论》 2024年第5期160-164,共5页
京津冀协同发展战略提出以来,三地协同发展取得积极进展,但距目标要求还有很大差距。本文选取2010—2019年京津冀地区高质量发展指标数据,利用因子分析法对各地区及整体发展水平进行综合评价,基于综合得分对其预警,并运用灰色预测分析方... 京津冀协同发展战略提出以来,三地协同发展取得积极进展,但距目标要求还有很大差距。本文选取2010—2019年京津冀地区高质量发展指标数据,利用因子分析法对各地区及整体发展水平进行综合评价,基于综合得分对其预警,并运用灰色预测分析方法,借助MATLAB软件对未来5年京津冀地区高质量发展情况进行预测。研究发现,京津冀地区整体高质量发展综合得分情况较好,但各地区发展综合得分还有一定的提升空间,且地区间存在差异,这种不均衡的发展态势为三地区未来协同发展提出了新的挑战。 展开更多
关键词 京津冀协同发展 高质量发展 地区经济 因子分析法 新发展理念
下载PDF
上一页 1 2 155 下一页 到第
使用帮助 返回顶部